1. Field of the Invention
The field of the present invention relates in general to the fields of internal combustion engines and air compressors. More particularly, the field of the invention relates to a dynamically reconfigurable multi-stroke computer programmable internal combustion engine with selectable cylinder component states, stroke sequences and changable cylinder firing order. The dynamically reconfigurable nature of the engine facilitates additional modes of operation that include compressed air production and storage, compressed air boost power, air compression braking, compressed air engine start, compressed air engine idle and combinations of these and other modes of operation.
2. Background
The internal combustion engine has seen thousands of improvements and developments. Some of the latest improvements include fuel efficiency, pollution reduction, electronic ignition, fuel mixture heating or cooling, fuel injection, variable displacement, air-fuel mixing and digital controlling of hydraulically actuated intake/exhaust valves. Camless hydraulically driven intake and exhaust valves and electronically controlled hydraulic fuel injectors are among the very latest innovations to impact internal combustion engines.
A computer processor that provides commands to electronic assemblies can finely control and vary valve actuation, fuel injection and ignition. Electronic assemblies process commands and feedback signals from these devices to manage engine operation. Camless valve control allows engine control subsystems to vary timing, lift, and compression ratio in response to engine load, temperature, fuel/air mix, and other factors. The electronic valve-control system improves performance while reducing emissions.
There are several methods of camless valve control. Sturman, U.S. Pat. No. 6,360,728 Control Module for controlling hydraulically actuated intake/exhaust valves and fuel injection, claim fast-acting electro-hydraulic actuators which provide mechanical means for valve actuation under the control of an electronic assembly. Solenoid actuated two-way spool valves can also be actuated by digital pulses provided by an electronic assembly. Camless technology brings the internal combustion engine under even more electronic control potential and away from inflexible mechanical controls.
There have been attempts to build engines that have variable displacement, using maximum displacement for high load requirements and switching to a lower displacement for lower power needs. These methods for variable power requirements have been tried and so far not met with great success.
Despite all the innovation, the internal combustion engine mindset is still, in the vast majority, a basic four-stroke engine. Thus, the past and current technologies are all focused on operation efficiency and improvement of a basic four-stroke internal combustion engine that operates strictly on the intake-compression-power-exhaust cycle. The internal combustion engine has four basic functions that correspond with each stroke; suction, compression, power, and exhaust. Engines that can take advantage of alternate stoke sequences and operation modes are needed, which would produce higher economies of operation, lower pollution emission, reduce add-on components and allow alternate utility of applicable uses.
Camshaft Constraints
Engine camshafts are typically permanently synchronized with the engine's crankshaft so that they operate the valves at a specific point in each cycle. Efforts to work around camshaft constraints have come in many forms, including variable-cam timing mechanisms. Variable-cam timing allows the valves to be operated at different points in the cycle, to provide performance that is precisely tailored to the engine's specific speed and load at that moment. If conditions require earlier valve opening and closing, for example, to achieve more low speed torque, the control logic commands solenoids to alter oil flow within the hydraulic cam timing mechanism, which rotates the camshafts slightly. If the valves should open later, to generate more high-speed power, the mechanism retards the cams as needed. However, the cam timing is moved forward or backward for all the cylinders on the cam-shaft, solidifying the dependences and constraints between cylinders. Furthermore, with limited exceptions, camshaft-using engines are constrained to the classic four-stroke internal combustion engine cycle.
Variable displacement engines are designed with cam-shafts of slightly different forms to add the option to effectively reduce or increase engine power by taking cylinders off and on power line respectively to follow power requirements and minimize waste. What are needed are ways to add more flexibility in internal combustion engines such that independent control of valve states and stroke sequences per cylinder unit can be achieved.
Turbochargers and Superchargers
Turbocharge and supercharge power boost systems for internal combustion engines compress intake air by exhaust turbo boosters or belt-driven blowers. They compress intake air to higher than atmospheric air pressure to increase oxygen density in the fuel mixture and thus increase fuel burn power. A turbocharger is an engine add-on, which generally comprises a pair of turbines mounted to a common shaft. One turbine is a drive turbine disposed in an exhaust flow path, while the other turbine is a compressor turbine disposed, conventionally into the intake flow path.
Turbochargers use engine exhaust gases discharged by the combustion chambers moving across the exhaust turbine to rotate it and the intake turbine thereby compressing gases in the fuel air mixture. This compression permits an increase in the amount of air introduced into each cylinder during the intake stroke of its piston while maintaining a desired fuel/air ratio, to produce an attendant increase in the engine's power output. Essentially, the turbocharger converts exhaust mechanical energy into compressed intake air with higher oxygen concentration.
Although these methods can increase an engine's power output, turbochargers have many deficiencies. At some operating points, turbochargers become unstable. A low RPM engine gives little exhaust flow to drive the turbine and high vacuum manifold conditions cause a reverse pressure differential in airflow through the compressor side that applies rotational forces to the compressor blade in opposition to the drive turbine. Thus, when exhaust flow is relatively low, the airflow-produced forces may be sufficient to cause reverse rotation of the compressor that renders a turbocharger inoperative. Most turbochargers do not engage until much higher than three thousand engine RPM for these reasons. In addition, the turbocharger is load following in that power must first be expended to produce exhaust that can advantageously turn the compressor. Turbocharger power is low or non-existent at low engine RPM and is ineffective in response to short stop-go engine driving because of these deficiencies. Turbos are useful when extra power is needed at high engine RPM. What is needed is a source of compressed air, enriched in oxygen, for engine power requirements that are not dependant on engine output but instead, independently feed compressed air into engine cylinders on demand.
U.S. Pat. No. 6,141,965, Charge air systems for four-cycle internal combustion engines, attempts to remedy some of the turbocharger deficiencies by compressing air with a small electric motor for engine RPM below 2500, a region where most turbochargers are ineffective, then switching to essentially classical turbo compression beyond 2500 RPM. This shows that there is a need for compressed air at lower engine RPM but the cost currently is an additional electric motor, complex conduit connections and an additional complexity in the control system. What is needed is a source of engine compressed air with settable engine speed independent compressed air densities, with minimal high maintenance add-on parts and unnecessary system complexity.
A supercharger develops high-density intake air by separately compressing intake air with the use of a rapidly spinning rotor that acts as a positive displacement air pump. Although these provide large increases in power and torque, the blowers drain energy from the engine crankshaft and generate high crankshaft friction losses that result in poor fuel economy.
Turbo boosters and superchargers are separate engine component add-ons that also add weight, unreliability and cost to engines. What is needed are methods that do not add complex components, maintenance costs or add disproportionately larger costs to vehicle engines than the benefits that they provide. What is needed are charged air sources which can provide extra boost power on driver demand regardless of engine RPM.
Compression Braking
Vehicles typically use friction brakes that throw away energy in the form of heat. Also, brake usage is not uniform. For a fully loaded truck, a full stop from 60 mph might raise brake drum temperatures to 600 degrees F. This is about the limit for safe operation. If the brakes are not well maintained, or the load is not distributed properly, then some brake drums might go to 800–1000 degrees F., which is dangerous. What is needed is a braking system to augment a friction braking system to reduce risk at peak brake use periods.
In order to compensate and reduce brake wear, drivers gear down the vehicle transmission, increasing the engine RPM, thus allowing the engine to perform work by suctioning air. Although effective in deceleration, this method wastes valuable energy in the form of suctioned air that cannot be used in power mode and heating while spinning up lower gears. However, the currently unchangeable four-stroke engine cycle prevents any further practical use of this wasted energy.
Many large diesel trucks and some larger RVs are equipped with “Jake Brakes,” also known as compression release engine braking systems. The basic idea behind a Jake Brake is to use the engine to provide additional braking power. A Jake Brake turns the engine into an air compressor to provide a great deal more braking power. Compressing the air in the cylinder takes power when the engine goes through a compression stroke.
A Jake Brake modifies the timing on the exhaust valves so that, when braking is desired, the exhaust valves open as the piston reaches the top of the compression stroke. The energy gathered in the compressed air is released, so the compression stroke actually provides engine braking power. The main advantage of a Jake Brake is that it saves wear on the normal brakes. This is especially important on long downhill stretches where brake shoes and linings can heat up in excess of 800 degrees F. The lasting disadvantage is that all of the compressed air that was used to brake is thrown away. What is needed are ways to store and reuse the compressed air thrown away in compression braking mode.
Intake Stroke
Much vehicle engine power is wasted in stop and go driving, an unwanted consequence of road and traffic conditions. During some of this time, drivers downshift transmissions to slow vehicles. If downshifted to provide braking, engine drawing in of intake air is used to slow the vehicle. Thus the intake stroke of the four-stroke engine has a braking feature while producing vacuum. However, the suction work produced by the engine is promptly thrown away. What is needed are ways to harness that wasted suction power.
Re-generative Braking
Some statistics indicate that 40% of engine power generated is eventually lost through braking. What is needed are regenerative braking systems which act to effectively brake a vehicle while incorporating methods to store and recover braking energy. What is needed are modes of engine operation that could produce, store and accumulate energy for later use.
Typically, brakes expend much more energy and more quickly than today's four-stroke engines can produce in terms of real-time engine braking. Re-generative flywheel approaches include such concepts as U.S. Pat. No. 4,171,029—Vehicle propulsion system with inertial storage, but the applications are generally not economically practical from added large costs and complexity above their utility values. What is needed are engines that can substantially slow a vehicle down without applying irreversible energy loss during frictional braking. What is needed are practical and economic methods of slowing a vehicle down by converting a vehicle's kinetic energy reversibly into potential energy. This would result in the capability of slowing a vehicle down, storing energy instead of losing energy through irreversible processes, and re-using the energy.
Vehicle Dependence on Battery
Most vehicles make heavy use of stored energy from a battery to start the engine. Other stored energy methods can be used to start an engine. Taking vehicle momentum, usually from an incline advantage, and turning the engine over without a starter motor can start most standard transmission vehicles. Along this fashion, compressed air can function as an alternate source of stored energy, which can, with the correct engine cycle configuration, be used to turn the engine crankshaft to start the engine. An engine with this capability would be more efficient due to the smaller energy conversion losses currently encountered from converting mechanical energy of the engine to electrical energy and back to mechanical starter motor energy. Further more, at engine start, the starting motor draws the largest single demand on the car battery without which a smaller battery may suffice. An alternative method of starting an internal combustion engine also adds reliability, and therefore value.
Hybrid Vehicles
Due to demands for more efficient engines, today's vehicle market is experiencing bifurcation from the typical four-stroke internal combustion engine to hybrid engines. Hybrids use electric motors and battery banks to improve fuel efficiency, adding power during acceleration and reclaiming energy when braking and coasting. Hybrid engines do not come without a price as the electric motors and battery banks add weight and cost to the vehicle, and generally reduce the size and therefore available power the of engine. In fact, most hybrid auto manufactures are still selling hybrids at a loss. What is needed are hybrid type engines that do not add weight and the cost of large, heavy battery banks, electrical generators and motors. Moreover, what is needed are hybrids that do not force engines to be smaller and lower power in order to be more efficient. Furthermore, what is also needed are hybrids that do not have conversion losses from engine power to electrical power and back from electrical power to mechanical power. What is needed are hybrids that transfer mechanical engine energy or vehicle momentum to recoverable energy forms which can be quickly re-introduced for engine or external uses, thus further extending the energy produced from combustion. While hybrids are a good future option to increase energy efficiency, what is needed are alternatives to the current single option, the electric-combustion hybrid engine.
Hydrogen Powered Vehicles
Some auto industry experts proclaim hydrogen will be the next fuel used to power vehicles and some car manufactures have built model hydrogen fueled cars. These have come in two very different technologies. One way is a hydrogen fuel cell electric vehicle. The other method is to use hydrogen to fuel an internal combustion engine. Here the hydrogen is combusted with oxygen to generate power, hence turbo and super charging increases engine power and idle engine strokes wastes fuel. Innovations to the internal combustion engine will be directly applicable to hydrogen fueled internal combustion engines of the future. A new Ford model hydrogen fueled internal combustion engine is optimized to burn hydrogen through the use of high-compression pistons, fuel injectors designed specifically for hydrogen gas, a coil-on-plug ignition system, an electronic throttle, and new engine management software. This engine requires supercharging, which provides nearly 15 psi of boost on demand, but the engine is claimed to be up to 25 percent more fuel-efficient than a typical gasoline engine. Much work is ongoing in this area and there is a continuing need to improve internal combustion engine performance, increase engine utility and efficiency while reducing engine waste and pollution.
Air Powered Engines and Idle
Vehicle numbers and traffic increases have substantially increased the time of even short distance travel. Furthermore, internal combustion engines typically remain in idle mode while the vehicle is waiting for stoplights, coasting, stalled in traffic, etc. The idle mode is fuel wasteful as any power is only used for keeping the engine crankshaft rotating so that flywheel rotation energy is preserved. An incline, or available compressed air source can serve the same function without use of more fuel. What is needed are ways to keep the engine crankshaft rotating during idle periods without additional fuel costs.
Currently, most engines use fixed mechanical cams to open and close valves. Fixed mechanical cams enforce a rigid valve opening and closing timing sequence regardless of external conditions and circumstance. For this reason, when power is not needed such as in low speed or halted traffic conditions, engine power is wasted by cylinder strokes working to draw in, compress, combust fuel and vent exhaust. This power is thrown out as a small waste that is not cost effective to harvest. Based on the current engine design, this is probably a good approach. What is needed are methods to use those small individual quantities of engine-produced compressed air that is otherwise discarded.
However impractical for most engine uses, U.S. Pat. No. 5,515,675 Apparatus to convert a four-stroke internal combustion engine to a two-stroke pneumatically powered engine demonstrates an attempt to use compressed air to power an engine. '675 is not an internal combustion engine but a pneumatic engine which consumes compressed air to push engine pistons in its single operating mode to turn a crankshaft. First, the compressing air source is an external artifice or contrivance outside of its engine cylinders. Second, the timing of valve opening and closing is done by a camshaft, substantially constraining the control of the valve states solely for application of compressed air to crankshaft power. And third, it employs a pneumatic distributor with a rotor which opens gate valves to supply compressed air to the cylinders, further precluding operation of any other engine modes save engine crankshaft power from compressed air.
In another invention using compressed air to power an engine, U.S. Pat. No. 3,980,152 Air powered vehicle claims an engine powered by compressed air from a suspension type air compressor, where the air compressor is operatively connected between a vehicle's wheel and chassis harnessing the vertical movement of the wheel due to unevenness of the road. While powering engines with compressed air has been an environmentally laudable idea, no air-powered engines have reached a practical standalone design or seen adoption to internal combustion engines as hybrids. What is needed are air-powered engines that can be powered with compressed air or by burning an air-fuel mixture, thus saving fuel and reducing environmentally harming gases produced from internal combustion engines. What is also needed are ways to take currently engine-discarded compressed air and re-direct that to compressed air energy useful applications.
Other Vehicle Applications Using Compressed Air
Motor vehicle systems themselves need a source of compressed air to operate their air brakes, air suspensions, automatic maintained air pressure tires, conformable air seats, re-usable airbags, etc. Automatically maintained air pressure tire systems require a source of compressed air to keep tires inflated. Ways are needed to produce a compressed air source for the myriad applications driven by compressed air. Furthermore, vehicles and vehicle power plants have many potential pneumatic applications currently using electrical power such as starting motors, window opening-closing mechanisms, etc., pneumatic applications which can benefit from a readily available compressed air source.
Air Compressors
Air compressors use gas or electric motors to compress air. Commercial uses of compressed air from mobile sources for building, and street contractors are well known and extensively used by a growing building and construction industry. Usually, this requires an expensive and separate gas or electric powered mechanical unit be brought to the work site. These vary in power and air volume needs depending on the application.
Almost all tools today for private or commercial use are powered by either electrical or pneumatic power. The pneumatic tools require a compressed air source. Hundreds of vendors supply thousands of various designs and capacities of air compressors, pneumatic tools requiring various capacities of compressed air, pneumatic tool components and other portable pneumatic equipment. There is a growing market for pneumatic tools, which is predicated on some source of compressed air, mobile or stationary.
A market that continues to grow, as pneumatic applications grow, offers the need for air compressors of various power, size, and capacity. Air compressors are continually advancing in the reliability and utility that they provide. However, they do need to be leased or purchased as separate units. These compressed air sources are based on the size of the job and length of time needed. There are thousands of pneumatic tools for home, commercial and recreational uses. From small 5 CFM capacity hand paint sprayers to 110 CFM capacity air hammers, capacity for tools and needs differs, determining the size of the air compressor source required. Because their use and need is variable and job dependant, planning and investment must be made in order to make economical use of air compressors.
Private uses for pneumatic tools and applications have increased over the years. Today, home repairs and maintenance can require rental or purchase of air compressors for such applications as sand blasting or spray painting the family home. Garage and home tools are also prime candidates for pneumatic applications.
Currently, these pneumatic applications require an independent air compressor and air storage tank, which typically includes an electric motor-driven reciprocating piston that compresses air and stores the compressed air in a tank. Since the basic four-stroke internal combustion engine produces vacuum, compressed air, power and exhaust, what is needed is an engine that can be reconfigured dynamically such that engine cylinders can produce power, compressed air and vacuum in a re-usable form and on demand. What is needed are engines which produce and store compressed air for later engine re-use and or use in external applications where a ready source of compressed air is available without the extra effort, ad-on equipment and expense of an external compressed air source.
Suction Pumps
Suction pumps and siphon applications generally require specialized equipment be brought in to siphon or collect debris. Work places need to be cleaned and vacuum is a good mechanism to collect debris and work by-product. Suction pumps serve many useful purposes in cleaning up spills or siphoning flooded volumes. These require some independent device such as a motor to be obtained to collect or gather scattered matter or fluid from one place to another. Since one of the strokes of a four-stroke engine (commonly called intake stroke) acts to suction, what is needed are ways to convert a four-stroke engine into a suction device when needed.
Engine Utility
Much has been done to improve internal combustion engines but there is still untapped utility in an internal combustion engine. What is needed is a utility engine analogous to a utility vehicle. An internal combustion engine which can go off regular power mode and provide utility needed for more than just power, such as compressed air or vacuum for external applications is needed. Since the current internal combustion engine has four strokes, what is needed are ways to fully utilize all of those strokes in alternate ways to increase the internal combustion engines usefulness.